Domestic kitchen food mixers generally use one of two different mechanisms for mixing ingredients; either two counter rotating beaters that are in a fixed position operating in a rotating bowl, or a single rotating orbital beater traveling around in a fixed bowl. The present invention relates to the former of these.
Two counter rotating beaters in a rotating bowl provide a very strong mixing action largely contained between the two beaters. Rotation of the bowl in this type of mixer is essential for effective mixing and bowls are therefore positioned on a turntable. Rotation may be induced either by directly driving the turntable or by relying on the friction of the rotating ingredients with the inside surface of the bowl. This is sometimes augmented by the provision of a small plastic button at the base of the outer beater, the rotation of the button with the beater assisting in rotating the bowl. This reliance on friction with or without an assisting button is only partially effective and, particularly with heavy mixtures the bowl may stop rotating which may in some cases even cause the bowl to be ejected from the turntable.
The rotating bowl allows for all ingredients to pass through the beaters which are positioned off centre and cover only about 25% of the bowl bottom at any one time. They are positioned in this way both to allow for the addition of ingredients while the mixing action is in progress and to allow the outer beater to scrape the inside surface of the bowl so as to incorporate unmixed material. Also it is often desirable to use a spatula to aid in the scraping of material from the inside of the bowl which the outer beater has been unable to remove.
A disadvantage of this type of mixer is that large and small quantities of ingredients cannot properly be mixed in the same size bowl so that normally at least two bowls are provided. A very small quantity, such as one egg white, for example can only be mixed in conventional mixers by use of a small bowl. In a large bowl, the small quantity spreads to cover the large bowl bottom and is then missed by the beaters which pass over the top.
In a small bowl however, the mixture is deep enough for the beaters to effectively “pick up” the ingredients and begin the process of mixing. But a disadvantage of a small bowl is that the adding of ingredients is restricted by the beaters which then occupy a large proportion of the bowl opening and which also prevent or render risky the introduction of a spatula for scraping the inside of the bowl.
There are further disadvantages in a two bowl system, including an increase in cost and of storage requirements. Also many recipes require that a mixture be started in a small bowl for later transfer to a large bowl with the associated inconvenience of extra work and additional cleaning up after use. To effectively position a bowl so that the fixed outer beater is adjacent the inner surface of the bowl requires that different size bowls be positioned on different rotational centres relative to the beaters. When the bowl is mechanically driven, providing two rotational centres becomes very complex and expensive.
Some mixers which do use a single bowl have generally compromised performance on small volume mixes or have restricted the bowl size to the extent that the mixer is unsuitable for large mixes. Other attempts to overcome the problems associated with small quantities have used a small diameter but deeper bowl. While this does allow a larger volume of ingredients it has the disadvantage of raising the height of the mixer and restricting access to the bowl for the addition of ingredients and the introduction of a scraping spatula.
Conventional mixers are considered to be of limited effectiveness in duplicating the mixing action traditionally provided by a manual whisk type beater. Beating eggs and other light materials requiring strong mixing by hand was, and may still be carried out with a beater made of a number of looped flexible wires attached to a handle which is rapidly passed through the mixture. Although the usual four blades of each of a pair of mixer beaters electrically driven at high speed appear to do a satisfactory job, there is a perception in the market place that an electric mixer needs some form of wire whisk type beater for light mixing.
It is an object of the present invention to address or at least ameliorate some of the above disadvantages.